In Enterprise Developer, because setting the RM Compiler directive sets the NOOPTIONAL-FILE Compiler directive, if you try to open a non-existent file for I-O or EXTEND the run-time system will give an error message. For I-O, RM/COBOL does the same. However, for EXTEND, RM/COBOL creates the file and opens it as if you had specified OUTPUT.
The following options are available: